There are many and various factors that can cause email servers to experience stress due to information overload. Examples are spam storms (and other mail related attacks), denial of service attacks, legitimate and illegitimate (albeit not illegal) mass marketing mailings, to name a few. Nevertheless, there are many instances where legitimate enterprises in furtherance of their business goals will want and need to disburse advertising and marketing information to interested consumers/customers.
Loyalty programs are marketing contrivances employed in many commercial sectors, such as, for example, retail (e.g. supermarket rewards cards, points cards, club cards, and the like) and commercial aviation (e.g. frequent flyer programs, etc.), that reward band loyalty. Typically, customers/consumers enrolled in the program accrue points and are entitled to discounts and/or rewards based upon pre-established criteria (e.g. distance flown on a particular airline, amount of produce purchased from a particular retail establishment, etc.). In order for loyalty programs and other mass marketing programs to keep their members apprised of various available offers, discounts, rewards and developments associated with these programs, many, if not most, have adopted electronic mail (email) as one of the preferred methods of communication to contact their members.
Typically, enterprises (e.g., commercial, educational, institutional, governmental, etc.) have substantial electronic mail infrastructure that for the most part is specifically constructed to satisfy a particular enterprise's unique requirements. While such electronic mail infrastructure may be perceived as being considerable, the electronic mail infrastructure utilized by organizations involved in mass marketing and/or loyalty marketing campaigns can be many orders of magnitude larger and more powerful than those ever conceived and/or required by typical enterprises. Thus when electronic mail infrastructure utilized by organization involved in mass marketing and/or loyalty marketing campaigns commence disseminating electronic mail related to the marketing campaign the volume of messages (e.g. in the tens of thousands to hundreds of thousands) that can be received by a typical enterprise electronic mail infrastructure can be so overwhelming that the typical enterprise electronic mail infrastructure will generally issue a transient error message. Transient error messages typically inform sending systems to try sending their messages later. This however has two major problems. First, there is no control as to when the sending system might try to resend the message; it might be 10 minutes, 4 hours, 1 day or never. Second, transient error messages cause a yo-yo effect since all global systems are effectively told to re-send their messages at some later time. So once the receiving mail server has recovered sufficiently to start accepting connections again, those systems that were told to re-send at a later time immediately re-send causing the receiving system to vacillate between issuing transient error messages and accepting connections for a period from anywhere between 24 to 48 hours.